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Modelling Macro Constants

modeling macro constants

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#1 littlepetinga

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Posted 29 July 2022 - 10:46 AM

Dear All

 

I am fitting some PK data with Phoenix ML Modelling. I am fitting the data with micro constant, but I also need to retrieve macro constants.

 

I selected WNL built-in model 11 (2cp micro xvas), but I can't understand which of the calculated secondary parameters are the macro constants I need (corresponding to A, Alpha, B and Beta when modeling with macro constants).

 

Many thanks in advance

 

Best regards

Sara

 


#2 bwendt@certara.com

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Posted 29 July 2022 - 11:58 AM

Hi Sara,

 

if you are interested in macro constants, you may want to use WNL model 13 (2cp macro xvas).

When you do that you would be able to compare the secondary parameters of WNL 11 with the primary parameters (Theta sheet) of WNL 13:

 

macro_constants.png

 

Values for Alpha, Beta, A and B can be mixed between the two models, e.g. A, alpha for WNL 11 could be B,beta for WNL 13.

 

Hope, this helps.

 

Bernd



#3 kniefort

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Posted 29 July 2022 - 02:57 PM

Hi Sara,

 

You can also uncheck use closed form, and then edit as textual.  This will give you the full PML model code and you can see the derivations of A, alpha, etc.

 

test(){
deriv(Aa = - Ka * Aa)
deriv(A1 = Ka * Aa - Ke * A1 - K12 * A1 + K21 * A2)
deriv(A2 = K12 * A1 - K21 * A2)
dosepoint(Aa, idosevar = AaDose)
C = A1 / V
error(CEps = 1)
observe(CObs = C + CEps)
stparm(Ka = tvKa * exp(nKa))
stparm(V = tvV * exp(nV))
stparm(Ke = tvKe * exp(nKe))
stparm(K12 = tvK12 * exp(nK12))
stparm(K21 = tvK21 * exp(nK21))
fixef(tvKa = c(, 1, ))
fixef(tvV = c(, 1, ))
fixef(tvKe = c(, 1, ))
fixef(tvK12 = c(, 1, ))
fixef(tvK21 = c(, 1, ))
secondary(Ktot = tvK12+tvK21+tvKe)
secondary(r1 = (Ktot^2-4*tvK21*tvKe)^0.5)
secondary(Alpha = (Ktot+r1)/2)
secondary(Beta = (Ktot-r1)/2)
secondary(Gamma = tvKa)
secondary(a1 = (tvK21-Alpha)/(Beta-Alpha))
secondary(b1 = (tvK21-Beta)/(Alpha-Beta))
secondary(KaAlpha = tvKa/(tvKa-Alpha))
secondary(KaBeta = tvKa/(tvKa-Beta))
secondary(aa = KaAlpha*a1)
secondary(bb = KaBeta*b1)
secondary(cc = -(aa+bb))
secondary(DoseOverVol = AaDose/tvV)
secondary(A = DoseOverVol*aa)
secondary(B = DoseOverVol*bb)
secondary(C = DoseOverVol*cc)
secondary(AUC = DoseOverVol/tvKe)
secondary(Cl = AaDose/AUC)
secondary(Alpha_hl = log(2)/Alpha)
secondary(Beta_hl = log(2)/Beta)
secondary(Tmax = CalcTMax(A,Alpha, B, Beta, C, Gamma))
secondary(Cmax = A*exp(-Alpha*Tmax)+B*exp(-Beta*Tmax)+C*exp(-Gamma*Tmax))
secondary(Ke_hl = log(2)/tvKe)
secondary(Ka_hl = log(2)/tvKa)
secondary(Cl2 = tvK12*tvV)
secondary(V2 = Cl2/tvK21)
ranef(diag(nV, nKa, nKe, nK12, nK21) = c(1, 1, 1, 1, 1))
}


#4 littlepetinga

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Posted 01 August 2022 - 10:42 PM

Hi Bernd

Hi kniefort

 

Thank you very much for your help!







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